Refrigeration compressor



Nov. 19, 1968 E. E. GROVER 3,411,705

REFRIGERATION COMPRESSOR Filed Nov. 29, 1966 CONDENSER I FIG. I. I 28 26 24 I M I I RESTRICTOR.

: :Oi b 0/ I--t J G 11 46 I is M no EVAPORATOR SUCTION PRESSURE TIME 62 WIT SSES INVENTOR fifx Elliott E. Grover.

a WY ZM W6 ATTORNEY United States Patent ABSTRACT OF THE DISCLOSURE Hermetic refrigeration compressor of the low-side type having Bourdon-tube valve means in the suction line leading from the suction space inside the hermetic compressor shell to the inlet of the compressor, the Bourdon-tube valve having a substantially closed position in the absence of compressor operation and being operatively connected to the intake of the compressor for operating the Bourdon-tube valve gradually from a closed to an open position upon startup of the compressor means for reducing the initial rate of pressure reduction in the suction space upon the startup of the compressor.

This invention relates generally to a hermetic refrigeration compressor of the low-side type, and in particular to such a compressor provided with means for limiting the initial rate at which the compressor can pump down the refrigerating system upon startup.

Low-side hermetically sealed compressors are arranged with the interior of the shell which encloses the compressor and motor in substantially open communication with the suction line leading from the evaporator of the refrigeration system. When the compressor is started after a nonoperating period during which the system as a whole has become warm from its environment (such as occurs with a typical window mounted room air conditioner, or a refrigerator), the suction side pressure is reduced relatively rapidly. The initial rapid reduction in pressure creates disturbing noises as well as imposing a high load upon the motor used to drive the compressor.

Accordingly the object of this invention is to provide means for controlling the rate of initial reduction in pressure at compressor startup, and thereby reduce the noise and torque demands typically associated with an overly rapid reduction of pressure. Y

In accordance with the invention, the passage of refrigerant gas from the suction space in the shell to the intake of the compressor is initially limited by valve means controlled by the suction developed by the compressor as it starts. In one currently preferred embodiment, the valve means may include a Bourdon-tube disposed to cooperate withopenings provided in an intake muffler. The tube is in communication with the intake conduit leading from the mufller to the intake valve port of the compressor and, as its arc tightens in response to the operation of the compressor, moves away from successive openings which admit refrigerant gas into the muffler.

The invention will be described in greater detail in connection with the accompanying drawing illustrating embodiments thereof by way of example, and wherein:

FIGURE 1 is a top view of one type of hermetic compressor unit to which the invention may be applied, this view illustrating the interior of the unit with the end head (i.e., top) of the shell removed, and showing the compressor unit connected to a schematically illustrated refrigeration system;

FIG. 2 is a vertical sectional view corresponding to one taken along the line II-II of FIG. 1 and illustrating the Bourdon-tube in a valve-closed position corresponding to non-operation of the compressor unit;

FIG. 3 is a vertical sectional view as in FIG. 2 but show- 3,41 1,7 05 Patented Nov. 19, 1968 ing the Bourdon-tube in a valve-open position corresponding to normal operation of the compressor unit;

FIG. 4 is a graph illustrating the relationship between suction side pressure and time during pump-down of a refrigeration system for both a conventional arrangement and an arrangement according to the invention; and

FIG. 5 is a view of a second embodiment according to the invention.

Most of the components of the compressor unit embodying the invention are conventional and thus will be only briefly described. The compressor unit shown in FIG. 1 includes an outer shell 10 to which the absent top end head is applied to provide the sealed interior suction space. Within the compressor unit cylinder housing 12, a horizontally reciprocating piston (not shown) is located. The connecting rod 14 connects it to an eccentric 16 turned by the shaft of an underlying electrical motor (not shown). A cylindrical head 18 provides interior passages 20 and 22 for the flow of intake and discharge gases, respectively, to and from the cylinder. The valve plate assembly 24 interposed between the cylinder head and the cylinder may be provided with conventional leaf valves to control the intake port 26 and the discharge port 28 of the cylinder. These passages and ports are schematically represented by dash line outlines since they may be conventional and take various forms.

The refrigeration system which the compressor unit serves is schematically illustrated with the principal parts identified by legend. Refrigerant gas leaving the evaporator is delivered by suction conduit 30 to the suction space interiorly of the shell 10. The discharge conduits 32 carry hot gas from the compressor unit to the condenser.

The path that the refrigerant gas must follow, after its discharge into the suction space from the open end of suction conduit 30, to get into the cylinder includes the intake mufller 42, tube 36 connecting the mufller outlet with the intake passage 20 in the cylinder head, and the intake port 26. After leaving the cylinder by way of discharge passage 22, the hot gas is pumped through tube 40 connected to the inlet end of discharge muffler 38, through the mufiler and its outlet tube 41 which extends through the shell interior in sealed relation thereto and connects to discharge conduit 32. By virtue of the suction conduit 30 being open to the interior of the shell, and the hot gas discharge path in the shell being closed, the compressor unit is characterized as of the low side type.

As noted before the preferred valve embodiment of the invention is associated with the intake mutiler 42. For purposes of the invention the mufiler provides a substantially closed chamber having an outlet to the cylinder and a valve controlled inlet. 'Inits illustrated form the muffler includes a pair of end members 42 and 44 which are substantially closed to the interior of the shell save for the outlet end of one, and a central cylindrical portion '46 provided with a number of spaced, gas inlet holes 48 in its wall. Except for these inlet holes 48, the interior of the mufiler is substantially out of communication with the suction space in the shell.

The degree to which the holes 48 admit gas into the mufller is controlled by the Bourdon-tube valve arrangement. As shown in FIG. 2, the Bourdon-tube 50 is provided with the requisite arcuate shape that, when relaxed by equalization of pressure inside and outside of the tube, it substantially covers the holes 48 with its outer circumferential area. The fixed open end of the Bourdon-tu be 50 is received in and carried by a fitting 52 secured in a wall of the central portion 46. This fitting has an interior passage which connects the Bourdon-tube with a bypass conduit 54 (FIG. 1) in communication with the intake conduit 36. Thus, the Bourdon-tube 50 is in communication with the intake of the compressor through a bypass around the mufller.

When the compressor operates, the suction produced by the intake strokes of the piston will reduce the pressure within the Bourdon-tube 50 which responds by gradually assuming the exaggerated tighter arcuate shape as shown in FIG. 3. This accordingly opens the ports 48 in the intake mufiier and permits refrigerant gas in the shell suction space to be drawn into the muffler. The gas flows through the perforated baffle 56 in the mufiier and then into the cylinder through the successive conduits and intake valve port. It is noted that as a practical matter the Bourdon-tube 50 need not seal perfectly against the openings 48 since adequate restriction is provided by an imperfect cover of these openings. By the same token,

the sections of the mufiier 34 need not seal completely with each other, and a bleed opening (not shown) may be provided in the fitting 52 to place the interior of the Bourdon-tube and connecting passages in restricted communication with the suction space in the shell.

The invention finds its greatest usefulness where the compressor is inoperative during periods when the temperature of the system can reach relatively high levels. Examples are window air conditioners which have been idle for a substantial period in a warm environment, and domestic refrigerators at the end of the defrost cycle. With the refrigerant gas at a relatively high temperature, say, 110 F., throughout the system, a correspondingly high pressure condition exists in the system, as contrasted to the normal suction pressure when the compressor is operating. When the compressor is then started without means provided to restrict the admission of gas into the compressor from the suction space, the pressure of the gas in the suction side of the system is initially reduced rapidly as is representatively illustrated by the solid line 58 in FIG. 4. The noise created by the pressure changes and associated loading within the system is substantially greater than after the compressor is operating at the normal stabilized condition. Also, the startup imposes a peak torque demand upon the motor driving the compressor. By using an arrangement according to the invention, the suction pressure reduction and associated loading is less severe initially, as indicated by the FIG. 4 dash line 60 representative of the suction pressure plotted against time during the period from the startup to a stabilized operating condition of the compressor.

The invention may of course be embodied in other forms. In FIG. 5 an embodiment of the invention is shown in which the gas from the suction space is admitted first to a slitted Bourdon-tube and then into the intake mufiier. The tube 62 is provided with a series of slits 64 in its outer circumferential surface. When the compressor is initially started, the reduction of pressure in the tube 62 causes it to assume a tighter arcuate form so that the slits 64 are correspondingly opened. Still another form may have the Bourdon-tube arranged to operate a butterfly valve through a mechanical linkage connected to the free end of the tube.

I claim as my invention:

'1. Refrigerant compressor apparatus comprising:

a hermetically sealed shell defining a suction space for low side operation of said compressor apparatus;

compressor means in said shell for drawing refrigerant gas from said space and compressing said gas;

means defining a path for the flow of said gas from said suction space to said compressor means;

valve means in said path having a substantially closed position in the absence of operation of said compressor means, irrespective of the pressure in said suction space; and

said valve means being operatively connected to the intake of said compressor means and responsive to compressor intake pressure for operating said valve means gradually from a closed to an open position upon startup of said compressor means to reduce the initial rate of pressure reduction in said suction space upon said startup.

2. Apparatus according to claim 1 wherein:

said valve operating means comprises a Bourdontube in communication with said compressor means.

3. Apparatus according to claim 1 wherein:

said path defining means includes an intake muffler in said shell having a series of openings in a circular Wall thereof; and

said valve means comprises an arcuately-shaped, ar-

cuately-flexible Bourdon-tube in communication with said compressor means, said Bourdon-tube being disposed in said mufiler and having a relaxed position substantially covering said openings.

4. Apparatus according to claim 3 including:

first conduit means connecting said mufiier to said compressor means; and

second conduit means connecting said Bourdon-tube to said first conduit means.

5. Apparatus according to claim 1 wherein:

said valve means in said valve operating means comprises an arcuately-shaped, arcuately-fiexible hollow tube closed at one end and in communication with said compressor means at its other end, the outer Wall of said tube having a series of transverse slits which are substantially closed in a relaxed posi tion of said tube and which open in response to suetion induced by operation of said compressor means.

References Cited UNITED STATES PATENTS 1,262,689 4/1918 Nelson 23030 1,519,996 12/1924 Wineman 230--31 1,796,796 3/1931 Le Valley 23030 X 1,903,853 4/1933 Ruff 230-30 X 1,968,985 8/1934 Black 230'-29 X 2,054,640 9/1936 Stenger 23030 X 2,529,349 11/1950 Nathan 230-29 2,571,420 10/1951 Churchman 23031 X 3,255,954 6/1966 Norlin et a1. 230-31 3,264,842 8/1966 Dob-b'ie 230-29 X 1,882,220 10/1932 Kercher 23029 FRED C. MATTERN, JR., Primary Examiner.

W. .T. KRAUSS, Assistant Examiner. 

